JP2009177901A - Uninterruptible power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a size and cost of an uninterruptible power supply device of a constant commercial-power feeding type. <P>SOLUTION: A load 19 and a bidirectional power conversion circuit 4 are connected to an AC input terminal 1 via an AC switch 2. An electric double-layer capacitor 5 is connected to a DC terminal 16 of the bidirectional power conversion circuit 4. The AC switch 2 is composed of a thyristor. A circuit for controlling the AC switch 2 so as to be continuously brought into an on-state, and a circuit for controlling the initial charging of the electric double-layer capacitor 5 are arranged at a switch control circuit 10 for controlling the thyristor of the AC switch 2. The thyristor of the AC switch 2 is phase-controlled at the initial charging. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an uninterruptible power supply having a backup power supply such as an electric double layer capacitor.

A typical uninterruptible power supply (hereinafter referred to as UPS) has an AC switch connected between an AC input terminal and an AC output terminal, a backup storage battery or capacitor, and a normal commercial AC voltage at the AC input terminal. Bidirectional power conversion that performs alternating current (AC) -direct current (DC) conversion operation to charge the storage battery or capacitor when supplied to the battery, and converts the DC voltage of the storage battery or capacitor to AC voltage when the commercial AC voltage is abnormal Circuit.

By the way, when a storage battery having a relatively large capacity is used as a backup power source of the UPS, the voltage drop of the storage battery due to self-discharge during the UPS stop period is small. Therefore, when the UPS is restarted after a long stop, the voltage of the storage battery is not a voltage that greatly falls below the end-of-discharge voltage, so that the storage battery can be immediately recharged by performing the AC-DC conversion operation of the bidirectional power conversion circuit.

On the other hand, when a capacitor with a relatively small capacity (for example, an electric double layer capacitor) is used as a backup power supply, the UPS voltage is stopped for a long time, and the capacitor voltage becomes zero or near zero by self-discharge. There is also. If the capacitor voltage is zero or a value close to this value and the bidirectional power conversion circuit starts an AC-DC conversion operation to start charging, an inrush current flows through the capacitor, resulting in an overcurrent state, fuse blown, etc. Protection works. Therefore, an initial capacitor charging circuit is required. In general, a dedicated initial charging circuit is used to initially charge the capacitor to a predetermined voltage when UPS operation is resumed, and thereafter, the bidirectional power conversion circuit is used for charging. However, providing a dedicated initial charging circuit inevitably increases the size and cost of the UPS.

Another method of initial capacitor charging is disclosed in Japanese Patent Laid-Open No. 2005-152519 (Patent Document 1). In the method described in Patent Document 1, a thyristor switch (AC switch) for disconnecting a load and an inverter from a commercial power source is connected between the commercial power source and the load, and the inverter is connected between the thyristor switch and the inverter. An inverter protection thyristor for disconnecting the inverter is connected, and when the electrolytic capacitor connected to the DC terminal of the inverter is initially charged, the inverter protection thyristor is phase controlled to control the charging current. However, in this method, since the inverter protection thyristor and the control circuit are provided, the UPS becomes large and expensive.
JP 2005-152519 A

  The problem to be solved by the present invention is that a small and inexpensive UPS is required, and an object of the present invention is to provide a UPS that can meet the above requirements.

In order to solve the above object, the present invention provides:
AC input terminal for connecting AC power supply,
AC output terminal for connecting the load,
An AC switch connected between the AC input terminal and the AC output terminal and having a function of controlling a current flowing through the AC input terminal;
It has an AC terminal and a DC terminal, the AC terminal is connected to the AC input terminal via the AC switch, and is connected to the AC output terminal without passing through the AC switch and converts DC to AC. A conversion switch and a diode connected in parallel to the conversion switch, and the conversion switch converts the alternating current to direct current. A bidirectional power conversion circuit configured to convert alternating current to direct current by the diode when not controlled to
Charge / discharge power storage means connected to the DC terminal of the bidirectional power conversion circuit;
Initial charge command signal generating means for generating an initial charge command signal indicating initial charge of the power storage means;
AC input voltage abnormality detection means for detecting an abnormality in the AC input voltage of the AC input terminal;
Connected to the conversion switch, the initial charge command signal generation means, and the AC input voltage abnormality detection means included in the bidirectional power conversion circuit, the output of the AC input voltage abnormality detection means indicates an abnormality. Sometimes, a DC-AC conversion control signal is supplied to the conversion switch, and at the same time that the initial charge command signal is not generated from the initial charge command signal generating means, the output of the AC input voltage abnormality detecting means indicates an abnormality. When the initial charge command signal is generated from the initial charge command signal generation means, the AC-DC conversion control signal and the DC-DC conversion control signal are supplied to the conversion switch. A conversion control circuit that does not supply any of the AC conversion control signals to the conversion switch;
The AC input voltage abnormality detection means, the initial charge command signal generation means, and the AC switch control terminal are connected to the initial state of the power storage means when the initial charge command signal is generated from the initial charge command signal generation means. The AC switch is controlled to flow a current required for charging, and the output of the AC input voltage abnormality detecting unit is abnormal at the same time that the initial charging command signal is not generated from the initial charging command signal generating unit. A switch control circuit for controlling the AC switch so that the maximum current required by the load or the maximum allowable current of the AC switch can flow when the load is not indicated. It relates to the power supply device.
The uninterruptible power supply in this application is substantially ignored not only when the switching time between the state in which power is supplied from the AC input terminal to the load and the state in which power is supplied from the bidirectional power conversion circuit to the load is zero. It also means that it is as short as possible (for example, ¼ cycle or less).

According to a second aspect of the present invention, the switch control circuit includes a constant current required for the initial charging of the power storage unit when the initial charging command signal is generated from the initial charging command signal generating unit. It is desirable to comprise a circuit for controlling the AC switch so as to flow.
In addition, according to a third aspect of the present invention, the switch control circuit switches on the AC switch so that the maximum current required by the load or the maximum allowable current of the AC switch can flow. Switch-on control signal generating means for generating a signal, phase reference signal forming means connected to the AC input terminal and forming a phase reference signal synchronized with the AC voltage of the AC input terminal, and a current flowing through the AC switch or Current detection means for detecting a charging current of the power storage means; current reference value signal generating means for generating a current reference value signal indicating a current reference value required for initial charging of the power storage means; and the current detection A current control signal comprising a signal indicating a difference between the current detection signal obtained from the means and the current reference value signal obtained from the current reference value signal generating means; A current control signal forming means for generating and selecting and outputting the current control signal obtained from the current control signal forming means when the initial charge command signal is generated from the initial charge command signal generating means; Signal selection means for selecting and outputting the switch-on control signal obtained from the switch-on control signal generating means when an initial charge command signal is not generated, and the phase reference obtained from the phase reference signal forming means Comparing means for outputting a switch control signal for controlling the conduction phase of the AC switch by comparing the signal and the output of the signal selecting means is desirable.
According to a fourth aspect of the present invention, the switch control circuit switches on the AC switch so that the maximum current required by the load or the maximum allowable current of the AC switch can flow. Switch-on control signal generating means for generating a signal, phase reference signal forming means connected to the AC input terminal and forming a phase reference signal synchronized with the AC voltage of the AC input terminal, and a current flowing through the AC switch or Current detection means for detecting a charging current of the power storage means; current reference value signal generating means for generating a current reference value signal indicating a current reference value required for initial charging of the power storage means; and the current detection A current control signal comprising a signal indicating a difference between the current detection signal obtained from the means and the current reference value signal obtained from the current reference value signal generating means; Current control signal forming means configured to compare the phase reference signal obtained from the phase reference signal forming means with the output of the current control signal forming means to control the conduction phase of the AC switch A comparator for outputting a signal; and when the initial charge command signal is generated from the initial charge command signal generator, the phase control signal obtained from the comparator is selected and output, and the initial charge command signal A signal selection unit that selects and outputs the switch-on control signal obtained from the switch-on control signal generation unit when no signal is generated, and a drive circuit that drives the AC switch by the output of the signal selection unit It is desirable to consist.
According to a fifth aspect of the present invention, it is preferable that the AC switch is composed of a thyristor.
Moreover, as shown in claim 6, the output switch connected between the interconnection point of the AC switch and the bidirectional power conversion circuit and the AC output terminal, the AC switch and the output switch A bypass switch connected in parallel to the series circuit, and the output switch is controlled to be turned off in response to the initial charge command signal generated from the initial charge command signal generating means, and the bypass switch Is preferably controlled to be turned on in response to the initial charge command signal generated from the initial charge command signal generating means.

The present invention has the following effects.
(B) Since the AC switch and its control circuit necessary for configuring the uninterruptible power supply are also used for current control for initial charging of the storage means, a special charging circuit for controlling the initial charging current is provided. Accordingly, the uninterruptible power supply can be reduced in size and cost.
(B) During the initial charging period, the power storage means (for example, an electric double layer capacitor) is charged via a diode connected in parallel to the conversion switch without specially controlling the conversion switch of the bidirectional power conversion circuit. Therefore, a special charging circuit for initial charging becomes unnecessary, and the uninterruptible power supply can be reduced in size and cost.
(C) The diode of the AC switch and the bidirectional power conversion circuit is an element through which the rated output current of the uninterruptible power supply device flows, and has a relatively large current capacity, and therefore sufficiently supplies the initial charging current required by the storage means. be able to.
According to a third aspect of the present invention, the phase reference signal forming means and the comparing means included in the switch control circuit are controlled when the initial charge command signal is generated and the initial charge command signal is generated. Since it is also used for control when there is no power, further miniaturization and cost reduction of the switch control circuit and the uninterruptible power supply can be achieved.
According to a fourth aspect of the present invention, the drive circuit included in the switch control circuit includes a control when the initial charge command signal is generated and a control when the initial charge command signal is not generated. Since they are also used, the switch control circuit and the uninterruptible power supply can be further reduced in size and cost.

  Next, an embodiment of the present invention will be described with reference to FIGS.

  1 is a continuous commercial power supply type AC uninterruptible power supply apparatus according to the first embodiment of the present invention, for example, an AC input terminal 1 connected to a 200V three-phase commercial AC power source, a three-phase AC switch 2, Three-phase AC output terminal 3, three-phase bidirectional power conversion circuit 4, electric double layer capacitor 5 as a storage means, input switch 6, output switch 7, bypass switch 8, AC input voltage AC input voltage abnormality detection circuit 9 as abnormality detection means, switch control circuit 10, conversion control circuit 11, first current detector 12, second current detector 13, and initial charge command signal generation means 14 and a DC switch 17. In addition, in FIG. 1 of the block display, all AC portions are configured in three phases.

  The AC switch 2 includes siris S1 and S2 having a function of controlling a current flowing through the AC input terminal 1 (conduction phase control function) and a function of ON / OFF control. The AC input terminal 1, the AC output terminal 3, Connected between. More specifically, the input terminal of the AC switch 2 is connected to the AC input terminal 1 via, for example, an input switch 6 having a mechanical switch structure, and the output terminal of the AC switch 2 is connected to, for example, an output switch 7 having a mechanical switch structure. Are connected to the AC output terminal 3. The AC switch 2 can be replaced with another semiconductor switch such as a triac (bidirectional control thyristor), IGBT, transistor, or FET, a combination of a semiconductor switch and a mechanical switch, or a combination of a plurality of different semiconductor switches. It can also be configured.

  The output switch 7 is connected between the interconnection point J 1 between the AC switch 2 and the bidirectional power conversion circuit 4 and the AC output terminal 3. The bypass switch 8 is connected in parallel to the series circuit of the input switch 6, the AC switch 2, and the output switch 7. The output switch 7 is ON-controlled during the OFF period, and the power supplied from the AC input terminal 1 is The load 19 is supplied via the AC output terminal 3. For example, during the initial charging period of the electric double layer capacitor 5, the output switch 7 is controlled to be off and the bypass switch 8 is controlled to be on.

  The bidirectional power conversion circuit 4 converts an AC voltage of the AC terminal 15 into a DC voltage and outputs the DC voltage to the DC terminal 16, that is, a converter function, and a DC voltage of the DC terminal 16. It has both a DC-AC (direct current-alternating current) conversion function, that is, an inverter function, which converts it into an alternating voltage and outputs it to the alternating current terminal 15. The AC terminal 15 of the bidirectional power conversion circuit 4 is connected to an interconnection point J1 between the AC switch 2 and the output switch 7. Details of the bidirectional power conversion circuit 4 will be described later.

  The electric double layer capacitor 5 as a power storage means is connected to a DC terminal 16 of the bidirectional power converter circuit 4 via a DC switch 17. In place of the electric double layer capacitor 5, another capacitor or a storage battery can be connected. Since the capacity of the electric double layer capacitor 5 is relatively small, the uninterruptible power supply of this embodiment is used as an instantaneous power failure compensation power source.

  The AC input voltage abnormality detection circuit 9 is connected to the AC input terminal 1 via the input switch 6 and detects a decrease in AC power supply voltage and an abnormality in overvoltage. When this is detected, the AC switch 2 is turned off, and both The direct power conversion circuit 4 is inverter-controlled. The AC input voltage abnormality detection circuit 9 compares the AC input voltage and the reference voltage with a comparator to detect a decrease or overvoltage of the AC input voltage, and controls the AC switch 2 to be on when normal and off when abnormal. This is a well-known circuit. The AC input voltage abnormality detection circuit 9 is also connected to the switch control circuit 10 via a line 20 and is also connected to the conversion control circuit 11 via a line 21.

  The first current detector 12 is a current transformer or magnetoelectric conversion element arranged to detect an AC line current between the interconnection point J1 and the AC terminal 15 of the bidirectional power conversion circuit 4. The detection signal is sent to the conversion control circuit 11 via the line 22.

The second current detector 13 is a current shunt or magnetoelectric conversion element arranged to detect a current of a DC line between the DC terminal 16 of the bidirectional power conversion circuit 4 and the electric double layer capacitor 5. The detection signal is sent to the switch control circuit 10 through the line 13a. Instead of providing the second current detector 13, the output of the first current detector 12 is sent to the switch control circuit 10 by a line 23 shown by a dotted line in FIG. 1 to control the conduction angle of the AC switch 2 in the initial charging. Can be used for etc. In this case, a rectifier circuit for rectifying the current detection signal on the line 23 indicated by a dotted line is provided, and the output of the rectifier circuit is used as a signal on the line 13a in FIG.

  The switch control circuit 10 continuously turns on the AC switch 2 (first and second thyristors S1, S2) when the AC input voltage is normal, and an AC input voltage abnormality detection circuit 9 detects an abnormality in the AC input voltage. And a function of controlling the phase of the AC switch 2 (first and second thyristors S1, S2) during the initial charging period of the electric double layer capacitor 5 (conduction angle control). The switch control circuit 10 is connected to the gates of the first and second thyristors S1 and S2 of the AC switch 2 for the above control. Details of the switch control circuit 10 will be described later.

  The conversion control circuit 11 performs an AC-DC conversion operation, that is, a converter operation so as to improve the waveform and the power factor of the bidirectional power conversion circuit 4 when the output of the AC input voltage abnormality detection circuit 9 is normal and does not indicate abnormality. When the output of the input voltage abnormality detection circuit 9 indicates an abnormality, the bidirectional power conversion circuit 4 is subjected to a DC-AC conversion operation, that is, an inverter operation. In order to enable the operation of the conversion control circuit 11, the output line of the conversion control circuit 11, that is, the control signal transmission line 26 is connected to the bidirectional power conversion circuit 4. Further, the AC terminal 15 and the DC terminal 16 of the bidirectional power conversion circuit 4 are connected to the conversion control circuit 11 by lines 27 and 28. In addition, the first current detector 12 is connected to the conversion control circuit 11 via a line 22, and the AC input terminal 1 is connected via a line 29. Details of the conversion control circuit 11 will be described later.

The initial charge command signal generation means 14 generates an initial charge command signal V15 shown in the period from t0 to t4 in FIG. 6D when the electric double layer capacitor 5 needs to be initially charged. To the switch control circuit 10, to the conversion control circuit 11 through the line 14b, and to the control terminals of the output switch 7 and the bypass switch 8 through the line 14c.

  FIG. 2 shows the three-phase bidirectional power conversion circuit 4 of FIG. 1 in detail. The bidirectional power converter 4 includes a first, second, third, fourth, fifth, and sixth diodes D1, D2, D3, D4, three-phase bridge connected to form a conversion switching circuit 30. First, second, third, fourth, fifth and sixth switches as conversion switches connected in reverse direction parallel to D5 and D6 and first to sixth diodes D1 to D6, respectively. Q1, Q2, Q3, Q4, Q5 and Q6. Although the first to sixth switches Q1 to Q6 are shown as insulated gate bipolar transistors or IGBTs in FIG. 2, they can be replaced by other controllable semiconductor switches such as FETs and transistors.

  The control terminals (gates) of the first to sixth switches Q1 to Q6 are connected to the conversion control circuit 11 of FIG. The interconnection point P1 of the first and second diodes D1 and D2, the interconnection point P2 of the third and fourth diodes D3 and D4, and the interconnection point P3 of the fifth and sixth diodes D5 and D6 are connected to the reactor. The circuit (inductor circuit) L and the capacitor filter circuit C are connected to the first, second and third AC terminals 15a, 15b and 15c, respectively. The first, second, and third AC terminals 15a, 15b, and 15c correspond to the AC terminal 15 in FIG. The reactor circuit L is composed of first, second and third reactors L1, L2 and L3 connected in series to each phase line, and functions as a waveform and power factor improving reactor during AC-DC conversion, that is, during converter operation. Furthermore, it functions as a step-up reactor, and also functions as a high-frequency component removal reactor during DC-AC conversion (DC-AC) conversion, that is, during inverter operation. The capacitor filter circuit C includes first, second, and third filter capacitors C1, C2, C3 connected between the first, second, and third AC lines. A high frequency component based on on / off of the switches Q1 to Q6 at a high frequency (for example, 10 or 20 kHz) is removed. The cathodes of the first, third and fifth diodes D1, D3 and D5 are connected to the first DC terminal 16a, and the anodes of the second, fourth and sixth diodes D2, D4 and D6 are the second DC. It is connected to the terminal 16b. The first and second DC terminals 16a and 16b correspond to the DC terminal 16 in FIG. A capacitor Co made of a high frequency capacitor or an electrolytic capacitor is connected between the first and second DC terminals 16a and 16b.

FIG. 3 schematically shows the inside of the conversion control circuit 11 of FIG. As apparent from FIG. 3, the conversion control circuit 11 includes an AC-DC conversion control circuit 31, a DC-AC conversion control circuit 32, a selective connection means 33, and a drive circuit 34. The AC-DC conversion control circuit 31 forms first-phase, second-phase, and third-phase control pulses for executing AC-DC conversion, and the DC-AC conversion control circuit 32 executes DC-AC conversion. First phase, second phase, and third phase control pulses are formed. The AC / DC conversion control circuit 31 and the selective connection means 33 connected between the DC-AC conversion control circuit 32 and the drive circuit 34 are a switching control signal for the first line 21 and an initial charge command signal V15 for the line 14b. When the switching control signal on the line 21 indicates commercial power supply, the signal on the output line 31a of the AC-DC conversion control circuit 31 is sent to the drive circuit 34 to switch the switching control signal on the line 21. When the (abnormality detection signal) indicates inverter power feeding, the signal of the output line 32a of the DC-AC conversion control circuit 32 is sent to the drive circuit 34. Further, the selective connection means 33 is connected to the drive circuit 34, the AC-DC conversion control circuit 31, and the DC-AC conversion control when the initial charge command signal V15 on the line 14b indicates the initial charge of the electric double layer capacitor 5 of FIG. The circuit 32 is disconnected. Instead of configuring the selective connection means 33 so that the AC-DC conversion control circuit 31 and the DC-AC conversion control circuit 32 are not connected to the drive circuit 34 during the initial charge, the connection between the selective connection means 33 and the drive circuit 34 is avoided. It is also possible to provide a switch in the switch and turn off the switch during initial charging. 3, the line 14b is connected to the AC-DC conversion control circuit 31 and the DC-AC conversion control circuit 32 as indicated by a chain line, and the AC-DC conversion control circuit 31 is initially charged at the time of initial charge by an initial charge command signal of the line 14b. The operation of the DC-AC conversion control circuit 32 can also be stopped. In short, the control by the line 14b can be replaced with any control that can turn off the first to sixth switches Q1 to Q6 during initial charging.

The drive circuit 34 connected to the selective connection means 33 is a well-known method based on the first-phase, second-phase and third-phase control pulses supplied from the AC-DC conversion control circuit 31 and the DC-AC conversion control circuit 32. Thus, signals for turning on / off the first to sixth switches Q1 to Q6 are formed and sent to the gates of the first to sixth switches Q1 to Q6 via the line 26. 3 indicate three lines, respectively, and the output line 26 of the drive circuit 34 indicates six lines.

An example of the AC-DC conversion control circuit 31 of FIG. 3 is shown in detail in FIG. This AC-DC conversion control circuit 31 approximates the waveform of the current flowing through the AC input terminal 1 in FIG. 1 to a sine wave during AC-DC conversion operation, controls the power factor close to 1, and controls the DC output voltage to a predetermined value. First phase, second phase, and third phase control pulses are generated. The AC voltage detection circuit 50 included in the AC-DC conversion control circuit 31 is connected to the AC input terminal 1 via the line 29 and the input switch 6 in FIG. The first, second and third phase AC voltages Va, Vb and Vc corresponding to the third phase voltage are output to the converter lines 51a, 51b and 51c and the inverter lines 52a, 52b and 52c. The first, second and third phase AC voltages Va, Vb, Vc of the converter lines 51a, 51b, 51c indicate the target sine wave for waveform improvement and power factor improvement. Instead of connecting the AC voltage detection circuit 50 to the line 29, it can be connected to the AC terminal 15 of the bidirectional power conversion circuit 4.

  The two voltage detection resistors 53 and 54 are connected to the DC terminal 16 of FIG. 1 via the line 28, and apply a voltage divided value of the DC terminal 16 to one input terminal of the error amplifier 55. The error amplifier 55 outputs a signal indicating the difference between the reference voltage of the reference voltage source 56 and the voltage detected by the voltage detection resistors 53 and 54 as the DC output voltage command value Vd.

  The first, second and third multipliers 57a, 57b and 57c are connected to the first, second and third phase AC voltages Va, Vb and Vc of the lines 51a, 51b and 51c, respectively, and the DC output voltage command of the error amplifier 55. Multiplying by the value Vd, the first, second and third phase command values Va'Vb ', Vc' are created. The first, second and third phase command values Va'Vb 'and Vc' correspond to the amplitudes of the first, second and third phase AC voltages Va, Vb and Vc modulated by the DC output voltage command value Vd. To do. A divider may be provided instead of the multipliers 57a, 57b, and 57c.

  The first, second and third subtractors 58a, 58b and 58c are connected to the first, second and third phase command values Va ', Vb' and Vc 'and lines 22a and 22b corresponding to the line 22 in FIG. , 22c, a signal indicating a difference from the three-phase current detection signal is formed. The first, second and third amplifier circuits 59a, 59b and 59c connected to the first, second and third subtractors 58a, 58b and 58c are the outputs of the first to third subtractors 58a to 58c. Is amplified or proportionally integrated or level-adjusted to output known pulse width control command signals V1, V2, V3 for the first, second and third phase converters. The first, second and third subtractors 58a, 58b and 58c and the first, second and third amplifier circuits 59a, 59b and 59c are integrated to form the first, second and third subtractors, respectively. It may be a difference signal forming means or a pulse width control command signal forming circuit for the first, second and third phase converters. The first, second, and third phase converter pulse width control command signals V1, V2, and V3 can also be referred to as first, second, and third phase converter PWM control command signals. Of course, the pulse width control command signals V1, V2, and V3 for the first, second, and third phase converters can be formed by circuits other than those shown in FIG.

  The triangular wave generator 60 as the converter comparative wave generating means can also be called a carrier generator, and is sufficiently higher than the frequency of the AC voltage of the AC input terminal 1, for example, 50 Hz, and higher than the audible frequency. For example, a known triangular wave voltage Vt is generated at a frequency of 20 kHz. The triangular wave generator 60 can be replaced with a sawtooth wave generator or a similar comparative wave generator. The amplitude of the triangular wave voltage Vt is set so as to cross the pulse width control command signals V1, V2 and V3 for the first, second and third phase converters.

  The first, second, and third converter PWM comparators 61a, 61b, 61c are the first, second, and third converters obtained from the first, second, and third amplifier circuits 59a, 59b, 59c, respectively. The converter pulse width control command signals V1, V2, and V3 are compared with the triangular wave voltage Vt of the converter triangular wave generator 60, and the first, third, and fifth AC-DC conversion control pulses G1, which are PWM signals, First, second and third phase control pulses Ga 1, Gb 2 and Gc corresponding to G 3 and G 5 are formed and sent to the drive circuit 34 through the selective connection means 33. The drive circuit 34 is a well-known circuit, and the first, third and fifth AC-DC conversion control pulses G1, G3, G3 corresponding to the first, second and third phase control pulses Ga, Gb, Gc, G5 is sent to the control terminals of the first, third, and fifth switches Q1, Q3, Q5 of FIG. 2, and the first, second, and second switches are provided by an inverted signal forming circuit (not shown) included therein. The second, fourth and sixth AC-DC conversion control pulses G2, G4 and G6 comprising the phase inversion signals of the three-phase control pulses Ga, Gb and Gc are formed, and the second, fourth and sixth switches are formed. Send to the control terminal of Q2, Q4, Q6.

  Since the DC-AC conversion control circuit 32 in FIG. 3 is a well-known circuit, details thereof are not shown. First, second and third phase DC-AC conversion control pulses Ga ′, Gb ′ and Gc ′ are supplied to the contact b of the selective connection means 33 in FIG. During the DC-AC conversion operation, the drive circuit 34 controls the first, second, and third phase control pulses Ga corresponding to the first, second, and third phase DC-AC conversion control pulses Ga ′, Gb ′, Gc ′. , Gb, Gc are formed and sent to the control terminals of the first, third and fifth switches Q1, Q3, Q5, and consist of phase inversion signals of the first, third and fifth switches Q1, Q3, Q5 Second, fourth and sixth DC-AC conversion control pulses G2, G4 and G6 are formed and sent to the control terminals of the second, fourth and sixth switches Q2, Q4 and Q6.

  FIG. 5 schematically shows a part of the switch control circuit 10 of FIG. That is, FIG. 5 schematically shows a control circuit for the first-phase thyristors S1 and S2 of the AC switch 2 shown in FIG. The control circuit for the second-phase and third-phase thyristors of the AC switch 2 (not shown) is configured in the same manner as the first-phase control circuit of FIG. Next, each part of FIG. 5 will be described in detail.

The switch control circuit 10 shown in FIG. 5 generates a switch-on control signal for turning on the AC switch 2 so that the maximum current requested by the load 19 or the maximum allowable current of the AC switch 2 can flow. A switch-on control signal generating means 71 is provided. This switch-on control signal generating means 71 is connected to the output line 20 of the AC input voltage abnormality detecting means 9 of FIG. 1, and in response to a signal indicating that the AC input voltage of the output line 20 is normal, FIG. A switch-on control signal V12 for turning on the AC switch 2 shown after time t4 in B) is generated. This switch-on control signal V12 is a signal that does not cross the sawtooth voltage V13, and turns on the first thyristor S1 during the entire positive half-wave period of the AC input voltage, and changes the first thyristor S1 during the entire negative half-wave period. 2 is a signal for turning on the thyristor S2 of the second. 6B, the level of the switch-on control signal V12 is determined so as to cross the sawtooth voltage V13 as indicated by a chain line, and the first and first phases are, for example, in the phase of 1 to 10 degrees of the half wave of the AC input voltage. Two thyristors S1 and S2 can be triggered, and a period from 1 to 10 degrees to 180 degrees can be set as a conduction period.

The phase reference signal forming means 72 included in the switch control circuit 10 shown in FIG. 5 forms the sawtooth voltage V13 shown in FIG. 6B as the phase reference signal, and the absolute value signal forming means 73 and And sawtooth voltage generating means 74. The absolute value signal forming means 73 is connected to the AC input terminal 1 via the line 29 and the input switch 6 of FIG. 1, and outputs an absolute value signal (rectified signal) V10 shown in FIG. The sawtooth voltage generating means 74 is connected to the absolute value signal forming means 73 and generates a sawtooth voltage V13 in synchronization with the rising of the absolute value signal (rectified signal) V10. Note that a periodic signal such as a triangular wave voltage can be output from the phase reference signal forming means 72 as a phase reference signal instead of the sawtooth voltage V13.

The switch control circuit 10 has charging current control signal forming means 75 for forming a charging current control signal for controlling the charging current of the electric double layer capacitor 5 to a constant value for initial charging. The charging current control signal forming means 75 includes a charging current reference value signal generating means 76 for generating a charging current reference value signal indicating a reference value of a current required for the initial charging of the electric double layer capacitor 5, and a calculating means 77. And a proportional integration circuit (PI) 78. The calculating means 77 is connected to the charging current reference value signal generating means 76 and the output line 13a of the second current detector 13 for detecting the charging current of the electric double layer capacitor 5, and the charging current reference value signal and the charging current detection signal are detected. A signal indicating the difference between is output. The proportional integration circuit (PI) 78 is connected to the calculation means 77 and proportionally integrates the output of the calculation means 77 to output a charging current control signal V11 shown in FIG.

The signal selection means 79 shown in principle in FIG. 5 includes a contact a connected to the charging current control signal forming means 75, a contact b connected to the switch-on control signal generating means 71, an output terminal c, and a control terminal d. And have. An initial charge command at a high level (first voltage level) at t0 to t4 (initial charge period) in FIG. 6D is applied to the control terminal d connected to the output line 14a of the initial charge command signal generating means 14 in FIG. When the signal V15 is input, the contact a is connected to the output terminal c, and the charging current control signal V11 of the charging current control signal forming means 75 is sent to the comparison means 80 in the next stage, which is shown after t4 in FIG. When the low level (second voltage level) initial charge command signal V15 is inputted, the contact b is connected to the output terminal c, and the switch on control signal V12 of the switch on control signal generating means 71 is sent to the comparing means 80. In FIG. 5, the signal selecting means 79 is shown as a mechanical switch. However, it is desirable that this is constituted by a semiconductor switch.

One input terminal of the comparing means 80 is connected to the phase reference signal forming means 72, and the other input terminal is connected to the output terminal c of the signal selecting means 79. This comparing means 80 compares the charging current control signal V11 of the charging current control signal forming means 75 with the sawtooth voltage V13 during the initial charging period from t0 to t4 in FIG. 6, and as shown by t1 to t2 in FIG. A pulse having a width corresponding to a period in which the charging current control signal V11 crosses the sawtooth voltage V13 is output, and after t4 (after the end of the initial charging period), the switch-on control signal V12 of the switch-on control signal generating means 71 and Compared with the sawtooth voltage V13, a high level thyristor continuous drive signal shown after t4 in FIG. 6C is output. The output signal V14 of the comparing means 80 is sent to the gate of the first thyristor S1 in FIG. 1 by the line 24 via the driving circuit 81, and sent to the gate of the second thyristor S2 in FIG.

  The operation of the uninterruptible power supply of FIG. 1 will be described. When charging the electric double layer capacitor 5 in an uncharged or incompletely charged state in a state where the voltage is normally supplied to the AC input terminal 1, the initial charge command signal generating means 14 sends t0 to t0 in FIG. As shown at t4, a high-level initial charge command signal V15 is generated. As a result, the bypass switch 8 is turned on, the output switch 7 is turned off, and the AC power supply voltage is supplied to the load 19 via the bypass switch 8. At the same time, the contact a of the signal selection means 79 in FIG. 5 is turned on, and the charging current control signal V11 shown in FIG. 6B for making the charging current of the electric double layer capacitor 5 constant from the current control signal forming means 75 is shown. Is output. The charging current control signal V11 is compared with the sawtooth voltage V13 in the comparison means 80, and a comparison output V14 composed of pulses shown in FIG. 6C is obtained. This comparison output V14 is sent to the gates of the thyristors S1 and S2 of the AC switch 2 via the drive circuit 81, and is conducted only for a limited time. The voltage obtained by controlling the phase of the AC voltage of the AC input terminal 1 by the AC switch 2 is input to the bidirectional power conversion circuit 4 and rectified by the diodes D1 to D6 shown in FIG. The Since the charging current of the electric double layer capacitor 5 is limited by the phase control of the thyristors S <b> 1 and S <b> 2 of the AC switch 2, no excessive current flows through the electric double layer capacitor 5. The selection connection means 33 included in the conversion control circuit 11 shown in FIG. 3 responds to the high level initial charge command signal V15 on the line 14b to the drive circuit 34 with the AC-DC conversion control circuit 31 and the DC-AC conversion. None of the control circuits 32 are connected. For this reason, the first to sixth switches Q1 to Q6 of the bidirectional power conversion circuit 4 are kept off during the initial charging period.

  When the initial charging period from t0 to t4 in FIG. 6 ends, the initial charging command signal V15 becomes low level, and the selective connection means 33 shown in FIG. 3 is normally supplied with voltage to the AC input terminal 1 of the line 21. In response to this signal, the AC-DC conversion control circuit 31 is connected to the drive circuit 34. At the same time, the contact b of the signal selection means 79 in FIG. 5 is turned on, the switch-on control signal generation means 71 is connected to the comparison means 80, and the thyristors S1 and S2 of the AC switch 2 are continuously turned on from the comparison means 80. A signal is output, and the AC voltage at the AC input terminal 1 is supplied to the load 19 and the bidirectional power conversion circuit 4 without being phase-controlled. At this time, the first to sixth switches Q1 to Q6 of the bidirectional power conversion circuit 4 are turned on / off so as to improve the power factor and the waveform.

  When a signal indicating normality of the AC input voltage is generated from the AC input voltage abnormality detection circuit 9 and the initial charging of the electric double layer capacitor 5 is unnecessary, the contact a of the selective connection means 33 shown in FIG. The AC-DC conversion control signal of the AC-DC conversion control circuit 31 is sent to the drive circuit 34, and the bidirectional power conversion circuit 4 performs an AC-DC conversion operation (converter operation). The capacitor 5 is charged.

  When a signal indicating an abnormality of the AC input voltage is generated from the AC input voltage abnormality detection circuit 9, the contact b of the selective connection means 33 shown in FIG. 3 is turned on, and the DC-AC conversion control signal of the DC-AC conversion control circuit 32 is turned on. Is sent to the drive circuit 34, the bidirectional power conversion circuit 4 performs a DC-AC conversion operation (inverter operation), and the AC voltage obtained from the bidirectional power conversion circuit 4 is supplied to the load 19.

This embodiment has the following effects.
(B) Since the AC switch 2 and its control circuit 10 necessary for configuring the uninterruptible power supply are also used for current control for initial charging of the electric double layer capacitor 5, a special current for charge current control It is not necessary to provide a control element or a dedicated charging circuit, and the uninterruptible power supply can be reduced in size and cost.
(B) During the initial charging period, the conversion switches Q1 to Q6 of the bidirectional power conversion circuit 4 are not specially controlled, and the electric power is transmitted via the diodes D1 to D6 connected in parallel to the conversion switches Q1 to Q6. Since the multilayer capacitor 5 is charged, a special AC-DC conversion circuit for initial charging is not required, and the uninterruptible power supply can be reduced in size and cost.
(C) The thyristors S1 and S2 of the AC switch 2 and the diodes D1 to D6 of the bidirectional power conversion circuit 4 are elements through which the rated output current of the uninterruptible power supply device flows and have a relatively large current capacity. The initial charging current required by 5 can be sufficiently supplied. That is, it is possible to charge the electric double layer capacitor with a large current at high speed (for example, in 1 second).
(D) The phase reference signal forming means 72 and the comparison means 80 included in the switch control circuit 10 are controlled when the initial charge command signal V15 is generated and when the initial charge command signal V15 is not generated. Therefore, the switch control circuit 10 and the uninterruptible power supply can be further reduced in size and cost.
(E) Since the output switch 7 and the bypass switch 8 are provided and the output switch 7 is turned off and the bypass switch 8 is turned on when the initial charge command signal V15 is generated, power is supplied to the load 19 even during the initial charge period. Can be supplied.

  FIG. 7 shows a modified switch control circuit 10a of the uninterruptible power supply according to the second embodiment. In FIG. 7, parts that are substantially the same as those in FIG. 5 are given the same reference numerals, and descriptions thereof are omitted. The switch control circuit 10a in FIG. 7 has substantially the same configuration as that in FIG. 5 except that the connection position of the signal selection means 79 is changed between the comparison means 80 and the drive circuit 81. That is, in FIG. 7, the current control signal forming means 75 is always connected to the comparing means 80. The contact a of the signal selection means 79 is connected to the comparison means 80, the contact b is connected to the switch-on control signal generation means 71, the output terminal c is connected to the drive circuit 81, and the control terminal d is the initial charge command signal V15. It is connected to the line 14a. The switch-on control signal generating means 71 outputs a high-level switch-on control signal V12 ′ for continuously turning on the thyristors S1 and S2 of the AC switch 2 (half-wave conduction period 180 degrees). It is configured as follows. In the second embodiment, the drive circuit 81 is used for both initial charging and normal operation. Therefore, the same effect as that of the first embodiment can be obtained by the second embodiment.

The present invention is not limited to the above-described embodiments, and for example, the following modifications are possible.
(1) Instead of the electric double layer capacitor 5, another electrolytic capacitor or a storage battery may be used. Further, the power storage means can be constituted by a combination of an electrolytic capacitor and a storage battery.
(2) The present invention can also be applied to a single-phase uninterruptible power supply.
(3) A switch for selectively disconnecting the bidirectional power conversion circuit 4 can be provided between the interconnection point J1 and the bidirectional power conversion circuit 4 in FIG.
(4) The bidirectional power conversion circuit 4 is not limited to the circuit shown in FIG. 2 and may be any circuit as long as both AC-DC conversion and DC-AC conversion are possible.
(5) A part or all of the switch control circuit 10 and the conversion control circuit 11 can be configured by digital arithmetic means such as a microcomputer or a DSP (digital signal processor).
(6) The input terminal of the AC input voltage abnormality detection circuit 9 can be connected to the output terminal of the AC switch 2.

It is a block diagram which shows the uninterruptible power supply device of Example 1 of this invention. It is a circuit diagram which shows the bidirectional | two-way power converter circuit of FIG. 1 in detail. It is a block diagram which shows the conversion control circuit of FIG. 1 in detail. FIG. 4 is a circuit diagram showing in detail the AC-DC conversion control circuit, selective connection means, and drive circuit of FIG. 3. It is a circuit diagram which shows the switch control circuit of FIG. 1 in detail. It is a wave form diagram which shows the state of each part of FIG. It is a circuit diagram which shows the switch control circuit according to Example 2 of this invention in detail.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC input terminal 2 AC switch 3 AC output terminal 4 Bidirectional power conversion circuit 5 Electric double layer capacitor 9 AC input voltage abnormality detection circuit 10 Switch control circuit 11 Conversion control circuit

Claims (6)

AC input terminal for connecting AC power supply,
AC output terminal for connecting the load,
An AC switch connected between the AC input terminal and the AC output terminal and having a function of controlling a current flowing through the AC input terminal;
It has an AC terminal and a DC terminal, the AC terminal is connected to the AC input terminal via the AC switch, and is connected to the AC output terminal without passing through the AC switch and converts DC to AC. A conversion switch and a diode connected in parallel to the conversion switch, and the conversion switch converts the alternating current to direct current. A bidirectional power conversion circuit configured to convert alternating current to direct current by the diode when not controlled to
Charge / discharge power storage means connected to the DC terminal of the bidirectional power conversion circuit;
Initial charge command signal generating means for generating an initial charge command signal indicating initial charge of the power storage means;
AC input voltage abnormality detection means for detecting an abnormality in the AC input voltage of the AC input terminal;
Connected to the conversion switch, the initial charge command signal generation means, and the AC input voltage abnormality detection means included in the bidirectional power conversion circuit, the output of the AC input voltage abnormality detection means indicates an abnormality. Sometimes, a DC-AC conversion control signal is supplied to the conversion switch, and at the same time that the initial charge command signal is not generated from the initial charge command signal generating means, the output of the AC input voltage abnormality detecting means indicates an abnormality. When the initial charge command signal is generated from the initial charge command signal generation means, the AC-DC conversion control signal and the DC-DC conversion control signal are supplied to the conversion switch. A conversion control circuit that does not supply any of the AC conversion control signals to the conversion switch;
The AC input voltage abnormality detection means, the initial charge command signal generation means, and the AC switch control terminal are connected to the initial state of the power storage means when the initial charge command signal is generated from the initial charge command signal generation means. The AC switch is controlled to flow a current required for charging, and the output of the AC input voltage abnormality detecting unit is abnormal at the same time that the initial charging command signal is not generated from the initial charging command signal generating unit. A switch control circuit for controlling the AC switch so that the maximum current required by the load or the maximum allowable current of the AC switch can flow when the load is not indicated. Power supply. The switch control circuit controls the AC switch so that a constant current required for initial charging of the power storage unit flows when the initial charging command signal is generated from the initial charging command signal generation unit. The uninterruptible power supply according to claim 1. The switch control circuit includes:
Switch-on control signal generating means for generating a switch-on control signal for turning on the AC switch so that the maximum current required by the load or the maximum allowable current of the AC switch can flow.
Phase reference signal forming means connected to the AC input terminal and forming a phase reference signal synchronized with the AC voltage of the AC input terminal;
Current detection means for detecting a current flowing through the AC switch or a charging current of the power storage means;
A current reference value signal generating means for generating a current reference value signal indicating a reference value of a current required for the initial charging of the power storage means;
Current control signal forming means for forming a current control signal comprising a signal indicating a difference between the current detection signal obtained from the current detection means and the current reference value signal obtained from the current reference value signal generation means;
When the initial charge command signal is generated from the initial charge command signal generating means, the current control signal obtained from the current control signal forming means is selected and output, and the initial charge command signal is not generated Signal selecting means for selecting and outputting the switch-on control signal obtained from the switch-on control signal generating means at times;
Comparing means for comparing the phase reference signal obtained from the phase reference signal forming means with the output of the signal selecting means and outputting a switch control signal for controlling the conduction phase of the AC switch. The uninterruptible power supply according to claim 1 or 2. The switch control circuit includes:
Switch-on control signal generating means for generating a switch-on control signal for turning on the AC switch so that the maximum current required by the load or the maximum allowable current of the AC switch can flow.
Phase reference signal forming means connected to the AC input terminal and forming a phase reference signal synchronized with the AC voltage of the AC input terminal;
Current detection means for detecting a current flowing through the AC switch or a charging current of the power storage means;
A current reference value signal generating means for generating a current reference value signal indicating a reference value of a current required for the initial charging of the power storage means;
Current control signal forming means for forming a current control signal comprising a signal indicating a difference between the current detection signal obtained from the current detection means and the current reference value signal obtained from the current reference value signal generation means;
Comparing means for comparing the phase reference signal obtained from the phase reference signal forming means and the output of the current control signal forming means to output a phase control signal for controlling the conduction phase of the AC switch;
When the initial charge command signal is generated from the initial charge command signal generation means, the phase control signal obtained from the comparison means is selected and output, and when the initial charge command signal is not generated, the switch Signal selecting means for selecting and outputting the switch-on control signal obtained from the on-control signal generating means;
3. The uninterruptible power supply according to claim 1, further comprising a drive circuit that drives the AC switch according to an output of the signal selection means. The uninterruptible power supply according to claim 1, 2, 3, or 4, wherein the AC switch includes a thyristor.   Further, an output switch connected between an interconnection point between the AC switch and the bidirectional power conversion circuit and the AC output terminal, and a parallel connection to a series circuit of the AC switch and the output switch The output switch is controlled to be turned off in response to the initial charge command signal generated from the initial charge command signal generating means, and the bypass switch is generated from the initial charge command signal generating means 6. The uninterruptible power supply according to claim 1, wherein the uninterruptible power supply is controlled to be turned on in response to the initial charge command signal.

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